Hot wire regulated mechanical movements



Jan. 19, 1965 H. J. KLINE HOT WIRE REGULATED MECHANICAL MOVEMENTS 3 Sheets-Sheet 1 Filed D60. 21, 1959 so n .VIO

INVENTOR HERBERT J. KL /NE 1 ATTORNEY Jan. 19, 1965 H. J. KLINE HOT WIRE REGULATED MECHANICAL MOVEMENTS 3 Sheets-Sheet 2 Filed Dec.

IN\ ENTOR HERBERT J. KL/NE ATTORNEY Jan. 19, 1965 H. J. KLINE 3,156,655

HOT WIRE REGULATED MECHANICAL MOVEMENTS Filed Dec. 21, 1959 3 Sheets-Sheet 3 INVENTOR HERBERT u. KL/NE ATTORNE United States Patent 3,166,655 HGT WIRE REGULATEB MECHANICAL MQVEMENT Herbert J. Kline, 21.6 E. High St, Jackson, Mich. Filed Dec. 21, 1959, Ser. No. 866,917 19 Claims. (iii; 290-113) The invention relates to improvements in snap action mechanisms and particularly in mechanisms wherein the regulating medium takes the form of an electrically heated longitudinally expansible and contractible element. This invention is a continuation in part of my copending United States application, Serial No. 512,675, filed June 2, 1955 now Patent No. 2,917,932. 7 Basically the mechanism of the invention consists of three linkage elements and a biasing force. ments are preferably arranged in an obtuse triangle formwith two of the elements being hinged or flexibly connected to each other and to the remaining element. To practice the novel advantages of the invention, the length between the connection points of the longest element-approaches, but is stopped from equalling, the combined connected length of the other two elements. the relation between the connected shorter elements to the longest element is that of a toggle joint.

In practice, one of the elements may be considered as being held in a fixed position with the biasing force being applied-to the other two elements which maybe characterized as the two movable elements. The direction of application of the biasing force is such that the height of the obtuse triangleformed by the elements tends to decrease towards zero with the-length of the longest element and the combined connected length of the other two shorter elements approaching equality.

With the acute angles betweenthe longest-element and fall of the cotangent values of this acute angle combined with the biasing force to effect the movement of the movable elements to and from the stopped position.

Obviously, a three-bar linkage of the above type is not movable unless one of the elements is extensible or c-ontractible and in thepractice of the invention, the longestlink consists of anelectrically heated member which longitudinally extends upon heating due to electric current passing .therethrough and contracts upon cooling;

The ele- Generally, the operation of my snap action mehanism.

is such that when extension of the-extensible element permits the biasing force to move the elements to a position beyond which the component of the biasing force A snap action movement in the opposite direction occurs and takes place under the following conditions: With the biasing force holdingthe elements in the stopped or collapsedposition, the contracting force due to cooling acts-to increase the resisting or restraining force i'n'the" relatively extensible element to the point at which it overcomes the component of the biasing force in that element, then the movable elements will rapidly move from the stopped position against the biasing force. Movement from the stopped position will cause a rapid decrease of the component of the biasing force acting upon the movable element and a correspondingly rapid release of the energy and force stored in the relatively extensible element by the contracting forces. This com bination of decrease of the component of the biasing force and simultaneous release of the stored energy derived from the contracting force provides a snap movement of the movable elements away from the stopped position. The stop position is determined by stop means acting directly against the movable member or indirectly by limiting the application of the biasing force to the linkage. Y

The advantages of snap action mechanisms are well manufactured, is dependable in operation, and may be readily calibrated to produce predetermined characteristics.

A further object of the invention is to provide a snap action mechanism for electrical switching controljsystems wherein a wide varietyof operating characteristics may be achieved by relatively simple modification, and uniform and consistent operation is obtained.

Yet another object of the invention is to provide a snap action mechanism employing a movable element wherein a plurality of snap action movements may be produced in sequence upon a unidirectional movement of.

the actuating element.

A further object of the invention is to provide a snap action movement of the type described Wherein'the elements are uar-r-anged'as an obtuse triangle, and one of the lengths of the triangle is in the form of a loop of one or more turns of electric resistance wire.

A further object of the invention is to provide an improved snap action mechanism having three elements defining an obtuse triangle, wherein two of the elements are movable and subject to a biasing force, and one of these elements is longitudinally extensible and contractible, and the third element is fixed and means are provided to selectively adjust the length of said fixed elemerits.

Another objectof the invention is to provide an electrically operated switch snap action mechanism which may be employed in a thermal relay wherein a high switching capacity is produced with a low energy input.

Another object of the invention is to provide a snap action switch mechanism which may be employed with thermal relays for operation in A.C. or DC. circuits of high or low voltage and wherein an easily adjustable time delay my be produced in either opening or closing the circuit.

These and other objects of the invention will be more fully understood from the following description and accompanying drawings, wherein: I

FIG. 1 is an elevational view of a simplified form of an apparatus employing'the concept of the invention,

FIG. 2 is. a plan view of another embodiment of a switching device,,in accord with the invention, wherein the contacts are located intermediate two wire loop arrangeme'nts and a flush mounting is provided,

' vention,

FIG. Sis a side elevatio nal view of the embodiment of FIG.4,

FIG. 6 is a bottom view of the embodiments of FIGS. 4 and 5,

FIG. 7 is a plan view of another embodiment of the invention which may be used as as circuit breaker,

FIG. 8 is a side elevational view of the embodiment of FIG. 7,

FIG. 9 is a plan view of another embodiment of the invention wherein two successive snap actions may be produced, 7

FIG. 10-is a side elevational view of the embodiment of FIG. 9,

FIG. ll is an end elevational View of the embodiment of FIG. 10 taken from the right end thereof,

FIGS. 12 through 14 are modifications of means which may be employed to vary the length of the compression member or links,

FIG. 15 is an elevational diagrammatic view of another embodiment of the invention,

pl-oyed as a current and voltage regulator.

The principle and operation of the linkage of 'the invention may :be best understood by describing the simplified form thereof as disclosed in FIG. 1 of the draw- 1 ings which may be used as a make and break switch or FIG. 3 is a side elevational view of the embodimentof spring 28 from pulling the link I14 downwardly. Upon' the flow of electric current, either A.C. or D.C., through relay. The linkage ismounted upon a support member 16 to which ismounted the 'fixed link 12. A movable link 14 is pivotally mounted to one end of the fixed link as at 16 and is provided with a pivot mounted in- 1 sulating knob 20 at its free end. A wire loop 22 consisting of one or more turns is passed around the knobs I8 and 20, and the ends of the loop are anchored upon the'knob 20 at terminals 24 fixed thereto. The wire employed in the loop 22 is of the electrical resistance I type and is of high strengthfor reasons which will be later apparent.

- 7 The wire loop 22., in effect, comprises the third member of an obtuse triangle, and as the forces within both sides of the loop are tensioned equally, the loop represents, in effect, a link, as illustrated by the broken line I 26;

10 and extends therefrom under the link 14. The spring a 28 isfixed to the link 14 by a connecting element 3%, I

and another leafspring 32 mounted 'to the support element extending below spring 28 mounts an'electric con-- upon the spring 28. Electric conductors maybe aii'ixed to the left end of the springs. v I

The wire within loop 22 is wound whereby the loop has a length which" will hold the three elements of the linkage in the position of FIG. 1, and it will be appr'eciated that the triangle in this position will be placed under stress due to the deflection of the leaf 28, as shown. The position of the elements as shown in FIG.- 1 is the open or cold position of the linkage, and the length of the connecting element St is determined as to deflect spring 28 as shown. The spring thus produces the biasing force necessaryth the operation of the linkage.

It will be appreciated that with the linkage in the 7 position of FIG. 1 that the links 12 and 14. will be'in compression and theloop 22 will be in tension.

The links 12 and 14 are of suflicient cross-section to withstand the extensive compressive forces imposed thereon,

' tact 34 for cooperation with an electric contact 36 formed the loop 22, the wire thereof will begin to heat, causing the wire to expand longitudinally. Upon suchexpanw sion of the wire loop, the forces exerted upon the linkage by the spring 23 will move the right end of link 14 downwardly and the triangle formed by-the linkage becomes progressively shallower. Continued expansion of the wire loop permits the spring 28 to continually move the link and wire loop downwardly in a rather slow motion, However, during this movement, the component of the biasing force produced by the spring in the wire loop is rapidly increasing, and upon this component exceeding the magnitude of the resistant forces within the loop, the biasing force, e.g.' the spring 28, will'move the link 14 and wire loop downwardly with increasing acceleration, and this increased acceleration constitutes the snap action. The spring 32 and contact 34 are posi tioned whereby the contacts 34 and 36 will engage as represented by the dotted lines. The spring 32 hasstiif characteristics wherein engagement of the contacts will stop the movement of the link, and the link' id will be in the position represented by the line 33.

Upon engagement of the contacts 34 and 36, the current is stopped from flowing through the loop 22, and the loop will begin to cool. As the loop cools, it'will contract and the tension forces therein will beginto build upward acceleration of the wire loop and link, the'link and wire loop continue to move upward slowly as the tension within the wire loop and the component produced by the spring 28 tend to equalize, and upon complete cooling of the wire loop, thelinkage will return to the position of FIG. 1. i 1

It will be thus appreciated that the movement of the linkage is a mechanical one and the snap action results from the very rapid increase of the component of the biasing force produced in the wire loop as the link ap: proaches the line 38. It will be understood that during the acceleration movement of the link and wire loop, the

wire loop is being stretched due to the fact that the link is pivoting about pivot '16. However, this stretching of the wire of loop 22 does not exceedthe yield point of the wire and, hence, thecharacteristics of the loop are not affected from cycle to cycle. The pressure with which contacts 34- and 36 engage may be varied by us'ing;a stronger or lighter biasing force and using greateror lower tension and compression forces in the links ofthe As the wire. loop may consist of one or many, turns, the electrical resistance produced bya loop may triangle.

be varied as desired and, hence, the wire loop may be usedas a resistance where accurate'temperature regulation may be produced with the line voltage and the use of auxiliary transformers and resistances is not necessary.

It should be noted that the link 1 must not pivotbelowthe line 49, which represents the extension of link 12, as the linkage would then be over-center and ren- OCCUITEI'ICC. 7

FIGS. 2 and 3 disclose another embodiment utilizing the concept of the invention to operate four pole double throw electric switch contacts, wherein a plurality of contacts are simultaneously opened or closed, and where- 'in the contacts are mounted intermediate'two spaced wire loops to provide clearance for the linkage movement. The device of this embodiment is mounted upon a support plate 42 on which is located'a'n electrical contact pileeup or. stackmounting contact supporting leaves 44 and 45 andcontact supporting leaf fingers 46 and 48, which pro ise be. of sufficient strength duce the biasing force necessary to operate thesnap action mechanism. g I,

The fixed and pivoted links of the triangular linkage are mounted upon the upper side of the supportplate 42, and both links are formed as portions 'of a single strip 50 of spring steel. The width of the strip 50 is substantially the same as the support plate, and the strip is centrally provided with a pair of holes to receive screws 52 which affix the strip to -the plate. As will be observed in FIG. 3, the central portion of the strip, in which the holes are formedfis upwardly bowed at 54, and a spring pressure plate 56 is interposed between the bowed portion and the nut element 58, into which both screws are threaded, whereby rotation of the screws 52 will depress the spring plate upon the bowed portion and hold the strip in firm engagement with the support plate 42. The portion 60 of the strip 50 serves as the fixed link and the portion 62 of the strip serves as the pivoted link. Due to the flexible character of the strip 50, the area 64 serves as a hinge interconnecting the fixed and hinged links. The insulating blocks of the stack firmly hold the fixed link 69 in engagement with the plate and prevent deformation ofthis link during operation of the device.

A pair ofinsulating knobs 66 and 66 are fixed. to one end of the hinged link 62 and another pair of insulating knobs 68 and 68' are fixed to the free end of the fixed link 64?. A pair of loops 70 and 70', each consisting of several turns of wire, are wound "about the knobs 66 and 68, and as and 68, respectively, and terminals fixed to the'knobs 68 and 68' provide anchorage means for the ends of the loops. The'longitudinal edges of the pivoted link portion 62 are deflected upwardly as at 72 to define flanges which reinforce the portion 62 and prevent the compressive forces interposed onthe link from buckling or deforming the link. It will thus be observed that the contact leaves and fingers are interposed between the two separate wire loops. j 7

An insulated adjustable bumper 74 is mounted upon the hinged link portion 62 to engage the contact finger spring 48, and another insulated bumper 76 interconnects the finger springs 46 and 48 whereby the movement of the hinged link portion 62 will be transmitted'to the finger springs, and likewise the biasing action of the finger springs will be imposed upon the hinged link.

The cold position of the components of this embodiment are as shown in FIG. 3, wherein the tension within the wire loops will maintain the finger springs biased upwardly. Upon the introduction of electric current through the wire loops 70 and 70, which are connected in parallel, the biasing force imposed on the link portion 62 by the finger springs 46 and 48 and leaves 44 will cause the portion to move downwardly and a snap action will occur wherein the contacts of leaf springs 45 will be engaged by the contacts mounted upon the finger springs.

The leaves 45 function as stops and upon engagementof the finger spring contacts with the contacts of leaves 45,

52, the plate 56 can be made to compress or flatten out the bowed portion 54 and thereby increase the length of the fixed link portion 66 Increasing'the length of the fixed link portion will cause the obtuse triangle to become greater in height due to the increased tension which the time of response of the switching device'can be made flanges 98 for reinforcement purposes. knob is afiixed to the free end of the hinged linkage 6 to vary as desired and manufacturingtolerances may be compensated This embodiment is easily mountable due to the lower flush surface of the support plate 42, and due to the use of a pair of spaced loops, high contact en gagement pressures may be created, if desired.

Another embodiment of the invention isillustrated in FIGS. 4 through 6, wherein similar components to those described above are employed. EoWever, they are arranged in a diiierent manner In the embodiment of FIGS. 4 through 6, the fixed and pivoted linkelements are mounted within the wire loop. In this embodiment, a stack '78 supporting a plurality ofleaves 8i), mounting contacts, and a pair of leaf fingers 82 and-84, also supporting electric contacts, are mounted to the under side of a support plate 86, and a strip including the fixed and hinged link portions 88 and 90, respectively, is affixed to the upper surface of the plate.

The strip comprising the fixed and hinged linkportions 88 and 90 of this embodiment. is similar to that of the embodiment of FIGS. 2 and 3 in that a bowed portion 92 cooperating with a spring pressure plate 94 is employed to selectively determine the length of the fixed link portion upon adjustment of the screws 96', and

the hinged link portion 90 is provided'with upturned An insulating 90 and an insulating knob 102 is afiixed to the free end of the fixed link portion 88. It will be noted that in this embodiment the insulating knobs must be of a relatively large thickness to permit the wire loop to encompass the linkage strip. The Wire loop 104 is afiixed to the terminal anchors .106 fixed upon'the insulating knob 102. I

A U-shaped element 108. having hooked ends engaging the link portion 90 on opposite sides of the insulating knob llii) supports a plate 112 on which is mounted an insulatedblock '114 which engages the contact fingers' 82 and 84. An adjusting screw 116 permits the block 114 to be'accurately adjusted relative to the plate 112,

and a locknut and screw arrangement. 118 permits the insulated block to be locked to the plate once the desired position thereto is achieved. The biasing force imposed on the linkage results from the spring tension produced by the contact fingers S2 and 84 and the leaves 80 immediately ther'eabove and, thus, when the linkage is in the cold position, the fingers will be deflected upwardly. The contact and finger relationship disclosed in FIG. 5 is that at the termination of the snap action. As in the embodiment of FIGS. 2' and 3, the embodiment of FIGS;

4 through 6 likewise employs the upper contact leaves 80 to augment the biasing forceproduced by 'the'finger leaves, and these upper contact leaves will additionally impose a biasing'force upon the contact leaves untilthe contacts of the finger leaves disengage those of the upper contact leaves. Vertical adjustment'of the insulating block 114 by means of screw 116 permits the snap action movement to be coordinated with the contact engagement of the finger leaves and contact leaves. i

Another embodiment of the invention is disclosed in FIGS. 7 and 8, and this embodiment is particularly adapted for use as a circuit breaker or a current limiting switch or relay. In this construction, the apparatus is mounted upon a support plate 120 having various portions thereon. An upstanding slotted projection 122 upon the support plate has a strip 124 mounted thereon having a bowed portion 126 and pressure plate 128 associating with adjusting and mountingscrews 130 wherein the fixed link portion 132 and hinged link portion 134 will be mounted upon the support plate. The free end of the hinged link portion 134 is provided with a pair of insulating knobs'136 and 138 separated by a spacer 140, and the free end of the fixed link-is provided with a single insulating knob 142. A single wire loop 144 is disclosed as being anchored upon knob 136 and passing 7 around knob 142 to be anchored to the lower side of the knob 138. Each of the knobs 136 and 138 are provided with contacts which they engage with a pair of contacts mounted upon spring leaves 146 amxed to the support 120 by screws. Thus, .the spring leaves 146 provide the current energizing the wire loop and this devicewill be connectedin series with the conductor line being pro- I tected'by the switch.

The hinged link portion 134 is reinforced by the upstanding. flanged edges .148, and a leafspring 150,

mounted in the upstanding projection 122, extends below the hinged leaf portion 134, and is afiixed thereto by brackets 152. As will be apparent from FIG. 7, the leaf spring 150 is formed in two parts providing a central I void as not to interfere with the wire loop. The leaf justed wherein a snap action motion will take placeand the contacts mounted upon-the leaves 146 and knobs 136 and 138'will separate to open the-circuit. The surface 154 upon the support base functions as a stop to prevent excessive movement of the linkage and when spring 159 bears thereon the biasing force is partially removed from the linkage and maximum contact separation is produced when the linkage engages the surface 154. Upon separation of the contacts, the wire loop 144 will cool and the linkage will return to a position r e-establishing the circuit. It will thus be appreciated that the invention provides "a circuit overload protection which will auto matically establish a circuit after a giventime. Adjush 'ment of the screws 130 will determine the time delay or time of response of the circuit breaker;

In some applications employing switching means, it is often desirable to operate contacts in a sequential manner, for instance, as in'a motor starting relay. The em- 'bodimentlof FIGS. 9 through 11 discloses one manner in which-the concept of the invention may-be employed to sequentially open a plurality of contacts upon a unidirec tional movement of the linkage, andwhereinjthe opening and closing of the contacts during each stage will be a snap action.

ing force, imposed on the linkage during the accelerated -rnovement thereof, wherein the component'of the biasing force within the extensible element, mainly the wire loop,

. is alternately greater and less than the tension force within the extensible element; thereby permitting at least two separate periods of acceleration to ;be achieved while the linkage is moving in a single direction.

. In the'embodimentof FIGS. 9 through 11, a support plate 156 has a pile-up or stack 158 mounted therebelow,

. and a linkage strip 160 mounted thereabove. The linkage st'rip'is similar to those of several of the previouslyde 7 the knob 172.

The pile-up 158 is mounted to one side of the support plate 156, as will be apparent from FIG. 11, and includes an upper'contact leaf 174 and; an intermediate contact leaf176, and a lower contact leaf finger 178, electrical pcontactsbeing affixed to each of the leaves. Stop leaves 130 are mounted upon the pile-up and are located directly below each of the contact leaves 174, 176 and 178,-'respec- Sequential operation, in accordance with the invention, may be accomplishedby varying the bias- .S V H tively. The stops are of substantially rigid' material and upon the leaf resting upon the associated stop, the stop prevents further downward movement thereof. It will be noted that the upper contact leaf 174 is mounted to one side of the center-line of the support plate 156 and that the intermediate contact leaf 174 is provided with an offset portion 182 which permits the lower contact .leaf .178 to be centered with respect to the support plate and hinged link portion 163, thereby permitting the biasing force exerted by the finger leaf 176 on the link portion 158 to be centered with respect to the linkfportion. By using the offsetpile-up arrangement, clearance is provided for movement of the linkage.

A U-shaped element 184 having hooked ends cooperates with the end of the hinge link portion 168 on opposite sides of the knob 17th as will be apparent from FllGSa9 and l1, and a plate 186 is atfixedtothe element 184.

An insulating block 138 is adjustably mounted to the plate by a screw and not 189 and has a hole defined therein for receiving the finger leaf 1'78. A hole defined in the plate 186 provides clearance for the extreme end of the finger leaf. Thus, the insulating block may be adjusted relative to the plate lhd to coordinate the snap action of the linkagewith the contact operation. v

a In operation, the linkage would beiin its"cold or up permost position wherein the contacts 1% an cl'192 and 194 and 196 would be in engagement and the contact leaves 174, 176 and 178 would all be biased upwardly and, hence, would constitute the total biasing force being imposed on the hinged linkage portion. As current flows through the wire loop- 173 and the wire loop begins to extend longitudinally, the considerable biasing force interposed on the linkagewill cause the hinged linkage.

portion and wire loop to move downwardly, as described above. force within the Wire loop becomingniuch greater than the resistance forces therein, the accelerated linkage movement will take place and open the contacts 194) and 1912. Upon opening of the contacts 1&9 and 192, the contact leaves 174 and1'76 will be engaging their respective stops 180 and, hence, the biasing force imposed on the linkage will be primarily that imposed by the contact leaf finger 178. As the biasing force component Within the wire loop imposed by the finger 178 is insuflicient to overcome the resistant forces therein necessary to produce accelerated movement of the linkage, the accelerated action will cease and continued heating of the wire loop is necessary to permit the second stage or second snap action to occur. As the wire loop continues to expand, the biasing force component in the wire loop taken place.

Upon cooling of the will then be additionally imposed upon the biasing force produced: bythe contact leaf finger 178, the upper movement of the linkage will be prevented until ufiicient coolmg takes place to overcome the biasing force component produced by the contact leaf ll'oand con-tact finger-173 of-thewire loop is very rapid, the time between stages to again provide another snap action closing the contacts 1% and 192;. Therefore, the snap action may occur both in opening and closing the contacts. If the cooling of'the two snap action sequences will be very short and in effect will consist of a single movement of the link portion 168 and conversely, upon a very rapid heating of the wire loop, the snap action sequencesopiening the contacts may be spaced very closely. together, timewise;

Thus, by employing a wire size for the loop of a pre- 1 determ ned area,and"providing a given resistance and Upon the component of the biasing wire loop, a reverse accelerated snap action will occur, engaging the contacts 194 and 1%, and as the biasing force of the contact-leaf 1'76" means for producing two sequential snap actions, it

will be appreciated that a similar arrangement may. be employed wherein possibly three or more snap actions may be sequentially produced.

FIGS. 12through 14 disclose enla-rged'detail views of various enmbodiments of means which may be used to vary the length of the fixed or hinged link of the linkage for purposes of adjustment. As described above, by providing adjustment means for the links under compression, the tension within the wire loop may be varied somewhat,and the "angles of the obtuse triangle of the linkage may be varied to thereby vary'the time response f the linkage snap action movement. The time of response of the apparatus of the invention will dependupo-n several factors, namely, the amount of current flowing through the wire loop and the cross-section area of the loop determines the-rapidity of heating of the loop and the resultant rate of expansionthereof and, secondly, the angular relationship of the links of the linkage wherein all other factors being equal, a triangle having a greater included angle between the fixed link and the wire loop linkage will require more movement of the pivoted link and the wire loop is of a smaller value and, hence a greater time delay response results. The use of the bowed portions to expand or contract the fixed link aifects the second condition as set forth above.

Referring to FIG. 12, the adjustment for the fixed link may include a corrugated curve 198 formed intothe strip 260 in which the fixed link and the pivoted link portions are formed. The disclosed corrugated strip portion is mounted upon a support plate 202 and a pressure plate 204 engages the upper portions of the curves. A screw 206, extending through a threaded hole inthe pressure plate and in the strip may vary the force exerted upon the curves by the pressure plate and thereby vary thevertical dimensions of the curves to lengthen or contract the length of the fixed link. It will be noted that the lower ends 208 of the'pressure plate also engage the linear portions of the strip, and this is a necessary relationship in that the ends 208 of the pressure plate firmly engaging the strip maintain the strip in engagement with the support plate, and prevent the strip from deflecting or raising above the support plate in the area adjacent the curves. Considering the hinged linkage to extend to the right of the embodiment of FIG. 12, it will be appreciated that the portion designated 210 of the strip will function as the hinge portion, permitting the hinged link to pivot relative to the fixed link.

Inthe' embodiment of FIG. 13, the fixed linkage consists of a pair of shoulder elements 212 and 214 which are mounted upon the support plate 216. ,A spring steel leaf is mounted in each of the shoulder elements, and the hinged link'218 is mounted upon the leaf 220 while an insulating knob 222 is affixed to the leaf 224. A convex spring pressure plate 226 is imposed uponv the'shoulder elements and the ends of the pressure pla'te'engage the shoulders thereof. The. screw 223 extending through a hole in the'spring plate is threadedly fixed to the support plate 216. Due to the configuration of the spring plate, the pressure exerted thereby upon the shoulder elements is in a downward direction, and thereby maintains the elements in firm engagement with support plate 216. While the forces imposed on the fixed link are compression forces, the shoulders and spring plate will efifectively re-' sist such forces and upon raising and lowering the screw 228, the distance separating the shoulder elements may be preadjusted,thereby, in effect, adjusting the length of the fixed linkage. V

It will be appreciated that .the longitudinal adjustment to vary the included angle between the'fixed element and it? the "wire loop need not be limited to adjustment of the fixed element, and that a similar eltect may be obtained by lengthening the pivoted or hinged linkage which is also in compression. The embodiment of FIG. 14 dis-.

closes a construction which may he employed'in the length of the pivoted linkage. In this construction, the pivoted linkage consists of two parts, namely, the 'portion 230 and the portion 232. The portion 23% is relatively thin cross-section and would preferably constitute a the hinge of the pivoted linkage. The shoulder 234 is defined upon the portion 232 and a threaded hole is formed therein to receive the screw 236. The portion 230 is bowed convexly at 238, and the spring pressure plate .246 is imposed between the bow and screwhead, wherein adjustment of the screw will vary the degree of height of the bow and the length of portion 230.

, FIG. 15 shows a diagrammatic side elevation view of yet another embodiment of the invention in the form of a relay operating a stack or pile of contact prongs or leaves.

The base support 242 carries the hinge bracket 244 for the hinged link 246, the limit stop 248 for the link 246, the mounting. pad 25%) for the stack of insulated contact leaves 252, 254, 256 and 258, and the pad or mounting face for the fixed link 259. I s

The hinged link 246 is hinged in the base support 242 at 26th and carries at its outer end a fixed knob 262 of suitable insulating material. A similar but bearing .re-

cessed knob 264 has a pivotal bearing on the fixed link 259 which bears against the mounting face 266 of the bracket 244 of the base support 242. Over these two in sulating knobs is wound one or more turns of suitable wire 263, the ends of which are secured to suitable anchorages 2'70 and 272 in the pivoted knob. These anchorages also serve as lead terminals. This is the input circuit of the relay.

The biasing load for the link 2:46 is provided by the long, double contact, load spring finger 274. The connection 277 between it and the link may or may not be of an insulating character depending on the particular use ,i the relay. In the up and down movement of the link 246, the load spring finger 274 will move from the upper tothe lower contact leaves 254 and 252, respectively, making the relay a single pole double throw type.

In the up or off position as shown, the load spring finger 274will bear against the upper contact leaf 254 which in turn, through the insulated bumper 276, pushes together the contacts of the, spring leaves 256 and 258. In the down or on position shown in dotted outline the load spring finger 274 will break contactwith upper contact will cause the wire to heat and expand in length. At a pre-' determined length the biasing force of the load spring 274 will snapthe link 246 to the down position against the stop 24% and shift the contact fingers. The contacts on the contact leaves 255 and 25% will open and cut into the circuit the resistance 278 whichwill reduce the current flow to that required to just maintain the link 246 in the down position. When the current flow is stopped the wire 26% will cool, contact and snap the link tion. I In some relays the current flow in the input circuit will be such that no additional resistance is required when the link 246is in the down position. This may be accomplished by using a wire 268 of a material having a high temperature coefficient of resistance. On the other hand by putting a potentiometer in the input circuit, various time delays can be effected in both the off to on and the on to off operation of the relay. Also, variations in the thickness of the thin resilient shim 2% between the base to the up or oif P0514 ll bracket-2 l i and the pivot support 259 can be used to efjfect various time delays as the shim 236i is another way of varying the length of the fixed link.

The basic principles of design and operation of the type of relay disclosed in this description may be embodied in the constructionof a wide variety of relays and con tactors torinany ditierentapplications and uses. The size may vary from a minute relay of very small capacity having as the operating element a single strand or turn of high resistant, high strength wire to a very large relay or contactor having many turns of active wire and controlling many hundreds of amperes of current carrying capacity. Also, for special purposes, conditions and advantages, these relays and kindred devices may be satis- I factorily operated enclosed in a vacuum, or various kinds of gaseous atmospheres, or immersed in a suitable liquid.

FIG. 16 shows a side elevation view of the invention in the form of a two circuit normally open contacts type It is for operation at 24 volts in the circuit shown. The operative or active element is six turns or 12 strands of .008 dia. stainless steel Wire 282 mounted over ceramic knobs 284 and 236 on the end of the hinged link 288 and on the fixed link 290, respectively. The ends of the wire 282 are secured to the metal anchorages 233 and'294 on the knob 286. The base support 292 is a right angled piece of heavy steel with one leg horizontal'2fi4 and a verticalleg 296. The vertical leg 296 carries the fixed link 290 on the inside face and the hinge recess 298 for the link 288 on the. outer face. The link 288is a rigid channel shaped steel stamping narrower at the outer end than at the hinge end. The horizontal leg 294? of the base support 292 carries the contact stack or pile 3% on the bottom face. The pile contains three contact fingers 302, 304, and 306. ,The middle finger 334 is the contact switchingfinger and also supplies the biasing forcefor the link 288., These two elements are connected by the'hook3tl8 on the end 310 of the contact switching finger304 and the pin 312 on theend314 of the link 288. a

The contact pile 394 also contains two stops. Under the upper contact finger 302 is a stop 316 to limit the downward movement of the finger and to permit an' initial load in it at the stopped position. Under the lower contact finger'306 is a heavy rigid member 318 that serves as the downward stop for the lower contact finger 306, the middle or biasing load contact finger 304 and in turn the link 288. The movable end 3200f the lower contact finger 336 is hooked under the outer end of the stop member 318 to permit limited upward movement of the con-' tact finger'306. I

The timing and cycling adjustment is made by shifting the fixed link 290 on the matching face of the base support 292 until the proper results are obtained and then sealing in place with adhesive cement. Sometimes a thin resilient the line c-b.

In operation when the manual switch 324 is closed the link 288 being up and the contact of the biasing load throwconstruction. The relays function to vary the in 3tl2and closing the contacts with the lower contact finger 306. This shunts the current flow from the stainless steel wire 282 and passes it directly to the lamps 330 in the circuit which now burn bright. The lamps 326 in 'the' secondary circuit go out because that circuit has been broken. The currentflow through it havingbeen shunted away, the active element of stainless steel'wi're 282 now cools and contracts, until lat a predetermined 'point it snaps the link 288 up, breaks the shunt, dims the lamps 330 and re-est'ablishes the currentfiow in the wire 232. Also the secondary circuit is re-established and the lamps 326 i The regulator comprises two relays-a current relay and a voltage relay and both are of the single pole single put to the field windings to control the generator output. The current relay 331 comprises a. single wire strand v 332,a right angled base support 334, a hinged link 336,

an insulated, fixed link 338,. and an insulated contact pile I 343. The contact pile consists of two'spring contact fin gers 342 and 344 and a rigid stop 350. The lower contact finger 342' also provides the biasing force for the link 336 :by means of an insulated connector 348. The rigid'stop .350 limits the downward movement of the lower contact finger 342 and also the link 336. In the down position the contacts of the two contact fingers 342 and 344 are separated. In the circuit the entire current output of the contact finger 304 being closed with the contact of the uppercontact finger 302, electric current flows through to the lamps 32 5 and to the battery 328. This is the secondary circuit and in this position of the'link 288 the lamps 326 burn bright.

At the same time current also flows through the active element of turns of stainless steel wire 282, then through the lamps 33d and to the battery 328. This is the primary circuit. The current is flowing throughthe steel wire 282, heats it and expands it in length, until at a predetermined point the biasng load of the finger 304 snaps the link 233 down,.opening the contacts with the upper contact finger generator 352 passes throughthe wire 332 of the relay 331. The voltage relay 354 has a loop 356 of a number of turns of high strength wire wound on insulating knobs 358 and 36% .mounted on the end of the hinged link 362 and bearing on fixed link 364, respectivelyf. In addition the relay354comprises a base support 366 and a contact pile 368 of two insulated contact fingers 370 and 372 and a rigid stop 374. The lower contact finger 370 also supplies the biasing force for the link 362 through the insulated connector 37 d. The rigid stop 374 limits the down- Ward movement of the lower contact finger 370 and the link 3152a Also in the down position the contacts on the fingers 37d and 372 are open. In the circuit the loop 356 is connected directly across the output line of the generator 352. V

In operation when'the current and voltage are below predetermined values then both links 336 and 362 will be up, all the contacts closed and the field winding 378 will be connected directly across the line. Now, when the current flow rises to a predetermined value the biasing contact finger 342 will'snap the link 336 down, on the current relay 331, open the contacts on fingers 3 32 and 344 and put in the field circuit a resistance 380'to 'limit the current output of the generator 352. And then if the voltage rises to a predetermined value it will cause increased current to flow through the wire ass of the voltage relay, heating it 'and expanding it to the point where the biasing load of the lower contact finger 370 will snap the link 362 down against the stop 374, open generator 352.

The effect of ambient temperature changes can be I I nullified by making all the metal parts of the relays 331 and 354 of the same material.

It will be thus appreciated that the apparatus of the invention provides a mechanical movement which is readily adaptable to operating a switching meansand'where in little power input is required to provide the actuating 7 few turns of resistance wire are required, the invention. may be economically produced when compared with more conventional switchingdevices employing coils having sev- .eral thousand turns wherein magnetic forces are employed to produce the switching movement. While a snap action is necessary in closing electric contacts to prevent excessive arcing and burning of the'contacts, the apparatus also inherently includes a time delay feature which is often desirable ina relay. By varying the number of turns in the wire loop and using'predetermined wire sizes, the response of the switching means may bereadily predetermined and the use of the adjusting screw to vary the length of'one of-the compression elements provides a very fine adjustment to precisely regulate the response duration. I

It is understood that various embodiments of the inlinkage for control or regulation purposes having at least two of its links angularly movable to control or, regulate, means constituting a biasing force applied to said linkage putting the longest link in tension loading and the shorter links in compression loading, one of said links being longitudinallyextensible or contractible under directly applied forces of control or regulation and in'the form of a long continuous metallic element comprising a loop of one or more turns and stop means restricting the'movements of said linkage; v

2. In alinkage as in claim 1 wherein said link in tension loading is the link in the form of a loop of one or more turns.

3. A snap-acting, three-link, shallow, obtuse, triangular linkage for control or regulation purposes having at least two of its links angularly movable to control or regulate, means constituting a biasing force applied to said linkage putting the longest link in tension loading and the shorter links in compression loading, said means constituting a biasing force comprising a plurality of biasing force creating means, said biasing force creating means being arranged to successively subtract from the total biasing force applied to said linkage upon movement thereof in one direction and successively .add to the biasing'force upon movement of the linkage in the opposite direction, one of said links being longitudinally extensible or contractible under directly applied forces of control or regulation and in the form of along continuous metallic element comprising a loop of one or more turns and stop means restricting the movement of said linkage.

4. A snap-acting, three-link, shallow, obtuse, triangular linkage for control or regulation purposes having at least two of its links angularly movable to control or regulate, a plurality of biasing force creating means producing a biasing force applied to said linkage putting the longest link in tension loading and the shorter links in compression loading, one of said links being longitudinally extensible or contractible under directly applied forces of control or regulation and in the form of a long continuous metallic element comprising a loop of one or more turns, a stop member associated with each of said means producing the biasing force wherein engagement of said biasing force creating means with a stop member during movement of the linkage varies the biasing force and, hence, the "acceleration of thelinkage causing the linkage to accelerate in successive stages. I

5. A snap-acting mechanical movement for control or regulation purposes comprising three members having a shallow, obtuse triangular arrangement, at least two of said members being angularly movable to control or regulate, at least one of said members being longitudinally extensible or. contractible under conditions of control or regulation, said lastfmentioned member being in a tengsioned condition and of a material-whereby the conduction of electric current through saidmaterial causes said member to longitudinally extend and means constituting a biasing force applied to at least one of said movable members.

6. In a mechanical movement as in claim 5 wherein the nonmovable member is mounted upon a support member and said means constituting a biasing force comprises a spring affixed to said support member operably associated with one of said movable members. i

; '7, In a mechanical movement as in claim 5 wherein stop means restrictthe movement of said movable members;

8. In a mechanical movement as in claim 7 -wherein said stop means are operatively associated with said means constituting a biasing force wherein said stop meanslimits the application of the biasing force.

9. In a mechanical movement as in claim 8 wherein electric switch contacts are supported adjacent said-movable members and means operatively interconnecting said movable members and said contacts whereby movement of said members activates said contacts.

10. A three-link obtuse angled linkage controlling electrical switching means comprising a support element, a first link fixed to said support element, a second link hingedly connected to said first link, a third link connect- .ed between the free ends of said first and second link thereby forming an obtuse triangle, said third link comprising a loop of one or more turns of electrical conducting wire, means connecting said loop to a control current, spring means imposing a biasing force on said second and third links placing said first and second links in compression and said third link in tension whereby upon elongation of said third link due to the heating thereof by a control current said second link will angularly move with increasing acceleration in the direction of the biasing force as said biasing force exceeds opposing forces, stop means limiting the movement of said second link, whereby upon contraction of said third link during cooling of said wire loop said second link moves with accelenation against said biasing force as opposing forces exceed said biasing force, electric contact means supported on saidsupport element and means operatively interconnecting said second link and said contact means Where by movement of said second link actuates said contact means.

11. In a linkage controlling switching means as in claim 10 wherein said first and second links are located within said wire loop.

12. In a linkage controlling switching means as in claim 10 wherein said third link comprises at least a pair of loops in spaced parallel relation.

13. In a linkage controlling 'switching means as in claim 12 wherein a plurality of leaf springs are afiixed to said support element and operatively associated with.

prising a loop of one or more turns of electrical conducting wire, means connecting said loop to a control current, spring means imposing a biasing force on said second and third links placing said first and second links in compression and said third link in tension Whereby upon elongation of said third link due to the heating thereof by a control current said second link will angularly move with increasing acceleration in the direction of the biasing force as said biasingforce exceeds opposing'forces, stop meanslimiting the movement of saidareaess Y exceed said biasing force, a plurality of electrical contact spring leaves mounted on saidsuppo'rt element in stacked relation, said leaves being stacked parallel to the second link, upon contraction of-said third link duringcooling of said wire loop said second link moves with v acceleration against said biasing force as'opposing forces exceed said biasing force, electric contact means supported "on said support element, and means adapted to selectively vary the length of a compression link to adjust the 'operating characteristics of the linkage.

16, In a linkage controlling switching means as in claim wherein said means selectively varying the link.

17. In a linkage cont-rolling switching means as in claim -15 whereinsaid means selectively varying the length of acompression link comprises a pair of shouldered members slidably mounted on said support element constituting said first link, a screwthreaded into said element intermediate said shouldered members and an arcuate bow' member engaging the shoulders of said shouldered members and'said'screw whereby said bow member maintains said'shoulder members upon said element and the configuration of said bow member-may be varied by said screw to vary the distancebetween said shouldered members.

18. A three-link obtuse angled linkage controlling electricalswitching means comprising a support element, a

first link fixed to said support element, a second link hingedly connected to said first link, a third link connected between the free ends of said first and second link thereby forming an obtuse triangle, said third link comprising a loop of, one or more turns of electrical conducting wire, means connecting said loop to a control current, spring means imposing a biasing force on said second and third links placing said first and second links in compression and said third link in tension whereby upon elongation of said third link due .to the heating thereof by a control current said second link will angularly move with increasing acceleration in the direction of the biasing force as said biasing force exceeds opposing forces, stop means limiting the movement otsaid second link, whereby upon contraction of said third link during cooling of said wire loop said second link moves with acceleration against said biasing force as opposing forces movement of said secorid'link, means continuouslyoperatively interconnecting one of saidleaves with said second link, electrical contacts aiiixe'd to said leaves whereby'the contacts of adjacent leaves are selectively engageable, said stop means associating with each of said contact leaves limiting movement of said leaves away from said second link, said stops and contacts being arranged whereby the leaves not continuously interconnected to said a second link contribute to saidfbiasing force -until engagement with their associated stopswhereupon movement of said second link decelerates until said third link extends sufiiciently to permit the remaining biasing force to again accelerate until'the leaf continuously interconnected to said second link engages its associated stop and hence ceases to contribute to the biasing.force.- i

19. A snap-acting, three-link, shallow, triangular link- I agefor control or regulation purposesphaving at least two of its links angularly movable to control or "regu late, the longest link being longitudinally extensible or 'contractible under directly applied forces of control or regulation and in the form of a long continuous metallic element comprising a loop of one or more turns, and a plurality of biasing force means and associated stop means operatiyelyconnected to said linkage putting the longest link in tension loading and the shorter links in compression loading,tand to provide a plurality of successive snap action movemnts in the direction of application of the biasing forces and also in the opposite direction thereof. r

References Cited in the file of this patent UNITED STATES PATENTS I 847,543 I Batault Mar. 19, 1907 1,408,307 Oakes Feb. 28, 1922 2,177,671 Schmidinger Oct. 31, 1939 2,700,084 Broekhuysen Jan. 18, 1 955 2,809,253 Broekhuysen Oct. 8, 1957' 2,811,603 Koch et 'al Oct. 29, 1957 2,817,731 De Falco Dec. 24, 1957 2,917,932 Kline Dec. 22, 1959 FOREIGN PATENTS 20,085 Great Britain Sept. 5, 1913 103,614 Austria June 25, 1926 1,175,065

France Nov. 10, 1958 

1. A SNAP-ACTING THREE-LINK, SHALLOW, OBTUSE, TRIANGULAR LINKAGE FOR CONTROL OR REGULATION PURPOSED HAVING AT LEAST TWO OF ITS LINKS ANGULARLY MOVABLE TO CONTROL OR REGULATE, MEANS CONSTITUTING A BIASING FORCE APPLIED TO SAID LINKAGE PUTTING THE LONGEST LINK IN TENSION LOADING AND THE SHORTER LINKS IN COMPRESSION LOADING, ONE OF SAID LINKS BEING LONGITUDINALLY EXTENSIBLE OR CONTRACTIBLE UNDER DIRECTLY APPLIED FORCES OF CONTROL OR REGULATION AND IN THE FORM OF A LONG CONTINOUS METALLIC ELEMENT COMPRISING A LOOP OF ONE OR MORE TURNS AND STOP MEANS RESTRICTING THE MOVEMENTS OF SAID LINKAGE. 